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Edexcel Biology Topic 5 (Monoclonal antibodies and antibiotics (Uses of…

- - - - A bacterium called Mycobacterium tuberculosis
      - Its symptoms are coughing and lung damage and it spreads through the air when infected individuals cough
      - The spread can be reduced/ prevented by infected people avoiding public spaces, practicing good hygiene and sleeping alone.
    - - A protist
      - Its symptoms are damage to red blood cells and in severe cases to the liver. It spreads using Mosquitoes acting as vectors- they pass it on without getting the disease themselves.
      - The spread can be prevented by using mosquito nets and insect repellent to stop them from biting people.
    - - It's a bacterium called Vibrio cholerae
      - Its symptoms are diarrhoea and it's spread via contaminated water sources
      - The transmission can be reduced/prevented by making sure that people have access to clean water.
    - - A bacterium called Helicobacter pylori
      - It causes stomach pain, vomiting and nausea and spreads via oral transmission.
      - The spread can be prevented/ reduced by having clean water supplies and hygienic living conditions
    - - Ebola virus
      - It causes haemorrhagic fever and is spread via bodily fluids.
      - The spread can be prevented/ reduced by isolating infected individuals and sterilising any area where the virus may be present.
    - - A fungus that infects ash trees
      - It causes leaf loss and bark lesions and is spread via the air by the wind. It can also spread when trees are moved between areas.
      - The spread can be prevented/ reduced by removing young, infected ash trees and replanting with different species. Also by restricting the import or movement of ash trees.
  - - - The virus attaches itself to a specific host cell and injects its genetic material into the cell.
        
        The virus uses proteins and enzymes in the host cell to replicate its genetic material and produce the components of new viruses.
        
        The virus components assemble
        
        The host cell splits open, releasing the new viruses, which infect more cells.
    - - The injected genetic material is incorporated into the genome of the host cell.
        
        The viral genetic material gets replicated along with the host DNA every time the host cell divides- but the virus is dormant and no new viruses are made.
        
        Eventually a trigger causes the viral genetic material to leave the genome and enter the lytic pathway.
    - - Chlamydia is a kind of bacterium but it behaves more like a virus because it can only reproduce inside host cells. Although it doesn't always cause symptoms, it can result in infertility in men and women. The spread of Chlamydia can be reduced by wearing a condom when having sex, screening individuals so they can be treated for the infection or avoiding sexual contact.
    - - HIV is the Human Immunodeficiency Virus and it kills white blood cells, which are really important in the immune response. HIV infection eventually leads to AIDS (Acquired Immune Deficiency Syndrome). This is when the infected person's immune system deteriorates and eventually fails - because of this, the person becomes very vulnerable to opportunistic infections by other pathogens. HIV is spread via bodily fluids and the main way to prevent it is using a condom during sex. Drug users should also avoid sharing needles.
        Medication can reduce the risk of an infected individual passing the virus on to others during sex so screening and proper treatment are also important.
- - - - Every pathogen has a unique molecule called an antigen on its surface which, after coming into contact with a B-lymphocyte, can be bound to by an antibody. The antibody is produced by the white blood cell and has a complimentary, specific shape. This stops the pathogen being harmful and allows it to be destroyed by another type of white cell. The antibodies are then produced rapidly and flow all around the body to target all the pathogens.
      - When a pathogen first enters the body, the specific immune response is quite slow wince the B-lymphocyte has to produce the right antibody to the antigen which can take some time. During this time, the person will show symptoms of the disease- eventually the body will produce enough of the antibody to overcome the infection. Memory lymphocytes are also produced at this time- memory lymphocytes are another type of white blood cell which stay in the blood for a very long time- they 'remember' the antigen. The person is now immune since their immune system now has the capacity to fight of this specific pathogen very quickly again. This is because if the pathogen enters the body again then there are more cells which will recognise it and produce antibodies against it. The secondary response is stronger and faster as well as the person will not show symptoms as the pathogen will be gone before this can happen.
      - Immunisation:
        
        This is the process of purposefully exposing someone to 'dead' or inactive antigenic pathogens in order to trigger an immune response against it. This means that antibodies can be produced against it despite it being harmless- this means that the person will produce memory lymphocytes to be made so if live versions of the same pathogen enter the body, the body can fight off the pathogen quickly and without the body showing pathogens.
      - The most important part of the immune system is the white blood cells. They go everywhere in your body waiting for pathogens. B-lymphocytes are part of a specific immune response.
      - PROS:
        
        Big breakouts of diseases or epidemics can be controlled and reduced if a large portion of the population are immune to the disease.
        
        Herd immunity comes about as a result of this because the people who aren't immunised have a lesser chance of catching it since there are less people who can pass it on.
        
        Diseases like smallpox have been virtually wiped out by immunisation programmes.
        
        CONS
        
        Immunisation doesn't always work as it won't always give you immunity.
        
        You can have a bad reaction to a vaccine like swelling or even seizures but bad reactions are very rare.